1. Field of the Invention
The invention relates to a sound and vision system comprising a display device and an acoustic transducer means.
The invention further relates to an electronic apparatus including such a system.
2. Description of the Related Art
International Patent Application No. WO-A/00/69212 discloses a small portable electronic article for personal use, such as a personal organizer or a mobile telephone, this article having a case provided with a keyboard or keypad, a visual display and a transparent cover over the display. The electronic article further comprises a loudspeaker composed of the transparent cover and a vibration exciter mounted on the transparent cover, the transparent cover thus serving as an acoustic radiator. Although the loudspeaker is incorporated in the known small personal portable electronics article in order to reduce weight and volume of the article, the possibilities to reduce, e.g., weight and volume seem to be not fully exploited.
It is an object of the invention to provide a sound and vision system in which the acoustic transducer means is further integrated in the system.
This object is achieved by the sound and vision system according to the invention, comprising a display device and acoustic transducer means, the display device including display cells having opposite electrodes, and conductive means connected to the electrodes in order to address said display cells, wherein the acoustic transducer means includes one or more of said display cells and the conductive means is electrically coupled to the acoustic transducer means. It is known that a display comprises a display electronic means for selecting and controlling the display cells, the display electronic means including said conductive means and the display cells of the display device incorporating electro-optical devices. In the sound and vision system according to the invention, the acoustic transducer means is virtually an integral part of the display device, the display electronic means, particularly its conductive means, being used for making an electrical connection to the acoustic transducer means for transmission of electrical signals to and/or from the acoustic transducer means.
The invention is based on the insight that it is possible to provide a sound and vision system with an acoustic transducer means by only or mainly making use of components already present in a known display device, without any significant loss of performance of the vision function itself. By means of this invention, which is the result of this insight, the number of components is reduced as compared with the known article, and further miniaturization of sound and vision systems is achieved. In general, the frequencies typically used to display visual data on a display screen only include low frequencies, particularly, the 50-60 Hz frame refresh rate, and very high frequencies, particularly, the data rate beyond 100 kHz. These frequency ranges fall outside the acoustic band normally used for speech audio of, e.g., a telephone, particularly, 300 Hz-3400 Hz, and practically fall outside the range of high performance audio, particularly, up to 20 kHz. Thus, a video addressing does not produce any undesired audio output, while, on the other hand, the display cells can be excited at intermediate audio frequencies without interfering with the video signals. It is to be noted that it is conceivable to use only the sound function of the system according to this invention.
An embodiment of the sound and vision system according to the invention is characterized in that the display device is a liquid crystal display device including a liquid crystal layer sandwiched between substrates. Especially liquid crystal materials xe2x80x94and effectsxe2x80x94which exert a strong mechanical force on the substrate are useful. Suitable examples of such materials are (anti)ferro electric liquid crystals, flexo electric liquid crystals and cholesteric texture liquid crystels. A prior art liquid crystal display device is disclosed in U.S. Pat. No. 4,723,838 (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the display device is an electrochromic display device including a material of which the color is switchable in dependence on an electric current or potential.
An embodiment of the system according to the invention is characterized in that the display device is an electrophoretic display device including an electrophoretic display medium sandwiched between conductors. A prior art electrophoretic display device is disclosed in the article 44.3L: A Printed and Rollable Bistable Electronic Display, P. Drzaic, et al.; SID98 Digest, pages 1131-1134; 1998 (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the display device is a reflective display device including an interferometric modulator. A prior art reflective display device is disclosed in the article 5.3: Digital Paper TM: Reflective Displays Using Interferometric Modulation, M. W. Miles; SID00 Digest, pages 32-35; 2000 (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the display device is a luminescent display device. A prior art luminescent display device is disclosed in U.S. Pat. No. 6,177,767 (herewith incorporated by reference). An embodiment of the system is characterized in that the electroluminescent display device includes an organic light-emitting device.
An embodiment of the system according to the invention is characterized in that the display device is a field emission display device. A prior art field emission display device is disclosed in article L2.1: Late-News Paper: A.4.5-in. Fully Sealed Carbon nanotube-Based Field-Emission Flat-Panel Display, W. B. Choi et al.; SID 99 Digest, pages 1134-1137 (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the display device is a foil display device. A prior art foil display device is disclosed in International Patent Application No. WO 00/38163 (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the display device is a plasma display device. A prior art plasma display device is disclosed in the paper ISSN 1083-1312/97/1701-0281; 1997 SID; Fabrication Techniques for High-Resolution 42-Inch HDTV PDP, M. Seki et al. (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the display device is a plasma-addressed liquid crystal display device. Such a device employs, with plasma display and liquid crystal display technologies, a display cell of the liquid crystal display device having with a physical electrode and a virtual electrode. The virtual electrode is formed by a charge layer produced by the plasma during operation. In this embodiment, the conduction means is connected, particularly electrically connected, to the virtual electrodes via the plasma. A prior art plasma-addressed liquid crystal display device is disclosed in the article 20.4L: Late-News Paper: Development of a 42-in. High-Definition Plasma-Addressed LCD, M. Hoyashi et al.; SID 99 Digest, pages 280-283 (herewith incorporated by reference).
An embodiment of the system according to the invention is characterized in that the acoustic transducer means is a loudspeaker, wherein, a vibration of a display cell is generated during use, by an electrostatic force produced by a voltage difference across the opposite electrodes of said cell. The loudspeaker includes or can be connected to an electric driving means, particularly a voltage source. By varying the voltage across opposite electrodes, a varying electrostatic force is generated for radiating sound from the display device, said force varying in a manner related to the varying voltage.
An embodiment of the system according to the invention, in which the acoustic transducer means is a loudspeaker, has a control means for selectively driving display cells. By selectively driving a number or all of the display cells, the display device can be used as a 2D loudspeaker array, offering the possibility to direct a beam of sound generated by such an array and to control the acoustic directivity. It is possible to generate a narrow beam of sound, e.g., radiated in a main beam directly into an ear. Alternatively, it is possible to divide the array in sub-arrays, each producing the sound of a particular sound channel, e.g., a left and a right channel, such that stereophonic sounds may be reproduced. The last-mentioned feature may be combined with technologies, such as, sound-base widening techniques. In other words, this embodiment enables the creation of complex acoustic patterns to either focus the sound or to expand the sound image. It is to be noted that such a control means is known per se. U.S. Pat. No. 4,233,472 (herewith incorporated by reference), e.g., discloses a circuit arrangement for a loudspeaker combination, the combination comprising a plurality of dynamic speakers which are arranged adjacent to each other in a continuous plane. The speakers may be arranged in line or in a two-dimensional configuration, the directivity pattern of the loudspeaker combination being determined by the circuit arrangement. Such an arrangement may be used as control means in the system according to the invention.
An embodiment of the system according to the invention is characterized in that the acoustic transducer means is a microphone, wherein, during use, a vibration of a display cell generates a voltage difference across the opposite electrodes of said cell. The acoustic transducer means can be a combination of a loudspeaker and a microphone.
It is to be noted further that U.S. Pat. No. 6,137,890 discloses a portable computer piezoelectric speaker, wherein a lid of a computer device serves as a rear speaker panel and a display screen of the computer device serves as a front speaker panel and wherein a piezoelectric actuator is located at or near the middle of a speaker panel for bringing the panel into vibration in order to radiate sound.
The electronic apparatus according to the invention, which apparatus may be a portable small apparatus, such as a mobile telephone, or a large apparatus, such as a TV set or a monitor, includes the sound and vision system according to the invention.
The above-mentioned and other aspects of the invention are apparent from and will be elucidated, by way of non-limitative example, with reference to the embodiments described hereinafter.